Patent GB-548138-A (GB)
Title: Improved system of inflation units for preventing the accumulation of ice upon airfoil surfaces of aircraft
IPC: B64D15/16
Filed: 1941-01-17
Abstract: 548,138. Valves. GOODRICH CO., B. F. Jan. 17, 1941, No. 693. Convention date, Jan. 19, 1940. [Class 135] [Also in Group XXXIII] For preventing the accumulation of ice on wings and other surfaces of aircraft a number of inflatable units is provided, each having a surface distortable by inflation of the unit, a number of distributer mechanisms individual to the units being supplied with fluid for inflating the units in alternation under the control of a common timing mechanism. Fig. 6 shows an aeroplane wing having four inflatable units 25-28 along its leading edge, two units 29 on the horizontal stabilizer and a unit 30 on the tail fin. Each of the units 25-28 has a separate distributer V<SP>1</SP>-V<SP>4</SP>. connected to pressure and suction pipes P, S. The units 29, 30 are controlled by a single distributer V<SP>5</SP>, the two units 29 being inflated and deflated together and alternately with the unit 30. The units comprise one or more inflatable tubes within a flexible cover depending on the thickness of the wing, the tubes in each unit being divided into two groups inflated alternately. The distributers V<SP>1</SP>-V<SP>5</SP> each comprises a casing 39, Fig. 1, in which a rotary valve 40, Fig. 2, is oscillated through 240 degrees by a rack 45 and pinion 44, a pin 51 on the rack actuating a reversing valve 49 of a power cylinder 48 so that the rack tends to reciprocate continuously. Movement of the valve is, however, rendered intermittent by the engagement of the plunger 54 of a solenoid 55, with a series of teeth a, b, c, don a disc 56 carried by the valve spindle. The valve casing has connections D<SP>3</SP>, D<SP>4</SP> to the two groups of tubes in the unit, a connection P<SP>2</SP> to the pressure pipe P, a connection S<SP>2</SP> to the suction pipe S, and a connection E to atmosphere. As shown, the connections D<SP>3</SP>, D<SP>4</SP> are in communication with the suction pipe connection and all the tubes of the unit are deflated. The solenoid winding is connected to a group of four contacts 57 ... 60 which co-operate with a continuously rotating contact finger T. Four such groups are shown, one for each of the distributers V<SP>1</SP> ... V<SP>4</SP>, the distributer V<SP>5</SP> being actuated simultaneously with one of the others. When the finger T makes contact at 57 the plunger 54 is momentarily raised and the valve rotates, counter clockwise, through 120 degrees when it is stopped by the tooth b. The connection D<SP>3</SP> is now in communication with the pressure connection P2. When the solenoid is again energized the valve rotates through the remairiing 120 degrees and the power cylinder reversed, but movement of the valve is prevented by the tooth c. In this position the connections P<SP>2</SP> and D<SP>4</SP> are in communication and the connection D<SP>3</SP> is put into communication with the exhaust passage E. At the next energization of the solenoid the valve rotates clockwise through 60 degrees to connect the passages D<SP>4</SP> and E, and at the fourth energization the valve assumes its original position. In a modified system each group of inflatable tubes is controlled by a separate valve actuated by a solenoid to put the tube alternately into communication with the pressure pipe and the suction pipe, a relief valve rapidly exhausting excess pressure when the valve is in the latter position. Such a valve is shown in Fig. 11 and comprises two pistons 91, 92, in a cylinder 90, urged apart by a spring 97. Their respective piston rods are connected to two valves 94, 96 the former normally closing the exit from a pressure chamber 99 and the latter normally putting a suction chamber 98 into communication with a chamber 100 connected to the inflatable tube. An outwardly opening valve 109 is provided on the chamber 98. When a solenoid 108 is energized a valve in a passage leading from the pressure chamber 99 to the opposite ends of the cylinder 90 is opened and the two pistons approach, causing the valve 96 to close and the valve 94 to open to inflate the tube through the connection D3. When the solenoid is de-energized the pressure on the pistons leaks away through a restricted part 90A and the valves assume their initial positions. The first rush of pressure air from the inflated tube opens the valve 109 after which the chamber 98 is exhausted through the suction connection S2. A modification is described in which the pistons are in separate cylinders at opposite ends of the valve casing and move outwardly when subjected to pressure from the pressure pipe. Fig. 10 shows another form of valve 73 directly moved by a solenoid 71 against the action of a spring 75, the connection D<SP>3</SP> to the inflatable tube being alternately connected to the pressure connection P<SP>2</SP> and the suction connection S2 which has a restricted passage 77. A valve 80 has a similar function to the valve 109 of Fig. 11.